/***
	Copyright (c) 2008-2009 CommonsWare, LLC
	Portions (c) 2009 Google, Inc.
	
	Licensed under the Apache License, Version 2.0 (the "License"); you may
	not use this file except in compliance with the License. You may obtain
	a copy of the License at
		http://www.apache.org/licenses/LICENSE-2.0
	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
 */

package com.commonsware.cwac.merge;

import java.util.ArrayList;
import java.util.List;

import android.database.DataSetObserver;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListAdapter;
import android.widget.SectionIndexer;

import com.commonsware.cwac.sacklist.SackOfViewsAdapter;

/**
 * Adapter that merges multiple child adapters and views into a single
 * contiguous whole.
 * 
 * Adapters used as pieces within MergeAdapter must have view type IDs
 * monotonically increasing from 0. Ideally, adapters also have distinct ranges
 * for their row ids, as returned by getItemId().
 * 
 */
public class MergeAdapter extends BaseAdapter implements SectionIndexer {
	private ArrayList<ListAdapter> pieces = new ArrayList<ListAdapter>();

	/**
	 * Stock constructor, simply chaining to the superclass.
	 */
	public MergeAdapter() {
		super();
	}

	/**
	 * Adds a new adapter to the roster of things to appear in the aggregate
	 * list.
	 * 
	 * @param adapter
	 *            Source for row views for this section
	 */
	public void addAdapter(ListAdapter adapter) {
		pieces.add(adapter);
		adapter.registerDataSetObserver(new CascadeDataSetObserver());
	}

	/**
	 * Adds a new View to the roster of things to appear in the aggregate list.
	 * 
	 * @param view
	 *            Single view to add
	 */
	public void addView(View view) {
		addView(view, false);
	}

	/**
	 * Adds a new View to the roster of things to appear in the aggregate list.
	 * 
	 * @param view
	 *            Single view to add
	 * @param enabled
	 *            false if views are disabled, true if enabled
	 */
	public void addView(View view, boolean enabled) {
		ArrayList<View> list = new ArrayList<View>(1);

		list.add(view);

		addViews(list, enabled);
	}

	/**
	 * Adds a list of views to the roster of things to appear in the aggregate
	 * list.
	 * 
	 * @param views
	 *            List of views to add
	 */
	public void addViews(List<View> views) {
		addViews(views, false);
	}

	/**
	 * Adds a list of views to the roster of things to appear in the aggregate
	 * list.
	 * 
	 * @param views
	 *            List of views to add
	 * @param enabled
	 *            false if views are disabled, true if enabled
	 */
	public void addViews(List<View> views, boolean enabled) {
		if (enabled) {
			addAdapter(new EnabledSackAdapter(views));
		} else {
			addAdapter(new SackOfViewsAdapter(views));
		}
	}

	/**
	 * Get the data item associated with the specified position in the data set.
	 * 
	 * @param position
	 *            Position of the item whose data we want
	 */
	@Override
	public Object getItem(int position) {
		for (ListAdapter piece : pieces) {
			int size = piece.getCount();

			if (position < size) {
				return (piece.getItem(position));
			}

			position -= size;
		}

		return (null);
	}

	/**
	 * Get the adapter associated with the specified position in the data set.
	 * 
	 * @param position
	 *            Position of the item whose adapter we want
	 */
	public ListAdapter getAdapter(int position) {
		for (ListAdapter piece : pieces) {
			int size = piece.getCount();

			if (position < size) {
				return (piece);
			}

			position -= size;
		}

		return (null);
	}

	/**
	 * How many items are in the data set represented by this Adapter.
	 */
	@Override
	public int getCount() {
		int total = 0;

		for (ListAdapter piece : pieces) {
			total += piece.getCount();
		}

		return (total);
	}

	/**
	 * Returns the number of types of Views that will be created by getView().
	 */
	@Override
	public int getViewTypeCount() {
		int total = 0;

		for (ListAdapter piece : pieces) {
			total += piece.getViewTypeCount();
		}

		return (Math.max(total, 1)); // needed for setListAdapter() before
										// content add'
	}

	/**
	 * Get the type of View that will be created by getView() for the specified
	 * item.
	 * 
	 * @param position
	 *            Position of the item whose data we want
	 */
	@Override
	public int getItemViewType(int position) {
		int typeOffset = 0;
		int result = -1;

		for (ListAdapter piece : pieces) {
			int size = piece.getCount();

			if (position < size) {
				result = typeOffset + piece.getItemViewType(position);
				break;
			}

			position -= size;
			typeOffset += piece.getViewTypeCount();
		}

		return (result);
	}

	/**
	 * Are all items in this ListAdapter enabled? If yes it means all items are
	 * selectable and clickable.
	 */
	@Override
	public boolean areAllItemsEnabled() {
		return (false);
	}

	/**
	 * Returns true if the item at the specified position is not a separator.
	 * 
	 * @param position
	 *            Position of the item whose data we want
	 */
	@Override
	public boolean isEnabled(int position) {
		for (ListAdapter piece : pieces) {
			int size = piece.getCount();

			if (position < size) {
				return (piece.isEnabled(position));
			}

			position -= size;
		}

		return (false);
	}

	/**
	 * Get a View that displays the data at the specified position in the data
	 * set.
	 * 
	 * @param position
	 *            Position of the item whose data we want
	 * @param convertView
	 *            View to recycle, if not null
	 * @param parent
	 *            ViewGroup containing the returned View
	 */
	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		for (ListAdapter piece : pieces) {
			int size = piece.getCount();

			if (position < size) {

				return (piece.getView(position, convertView, parent));
			}

			position -= size;
		}

		return (null);
	}

	/**
	 * Get the row id associated with the specified position in the list.
	 * 
	 * @param position
	 *            Position of the item whose data we want
	 */
	@Override
	public long getItemId(int position) {
		for (ListAdapter piece : pieces) {
			int size = piece.getCount();

			if (position < size) {
				return (piece.getItemId(position));
			}

			position -= size;
		}

		return (-1);
	}

	@Override
	public int getPositionForSection(int section) {
		int position = 0;

		for (ListAdapter piece : pieces) {
			if (piece instanceof SectionIndexer) {
				Object[] sections = ((SectionIndexer) piece).getSections();
				int numSections = 0;

				if (sections != null) {
					numSections = sections.length;
				}

				if (section < numSections) {
					return (position + ((SectionIndexer) piece)
							.getPositionForSection(section));
				} else if (sections != null) {
					section -= numSections;
				}
			}

			position += piece.getCount();
		}

		return (0);
	}

	@Override
	public int getSectionForPosition(int position) {
		int section = 0;

		for (ListAdapter piece : pieces) {
			int size = piece.getCount();

			if (position < size) {
				if (piece instanceof SectionIndexer) {
					return (section + ((SectionIndexer) piece)
							.getSectionForPosition(position));
				}

				return (0);
			} else {
				if (piece instanceof SectionIndexer) {
					Object[] sections = ((SectionIndexer) piece).getSections();

					if (sections != null) {
						section += sections.length;
					}
				}
			}

			position -= size;
		}

		return (0);
	}

	@Override
	public Object[] getSections() {
		ArrayList<Object> sections = new ArrayList<Object>();

		for (ListAdapter piece : pieces) {
			if (piece instanceof SectionIndexer) {
				Object[] curSections = ((SectionIndexer) piece).getSections();

				if (curSections != null) {
					for (Object section : curSections) {
						sections.add(section);
					}
				}
			}
		}

		if (sections.size() == 0) {
			return (null);
		}

		return (sections.toArray(new Object[0]));
	}

	private static class EnabledSackAdapter extends SackOfViewsAdapter {
		public EnabledSackAdapter(List<View> views) {
			super(views);
		}

		@Override
		public boolean areAllItemsEnabled() {
			return (true);
		}

		@Override
		public boolean isEnabled(int position) {
			return (true);
		}
	}

	private class CascadeDataSetObserver extends DataSetObserver {
		@Override
		public void onChanged() {
			notifyDataSetChanged();
		}

		@Override
		public void onInvalidated() {
			notifyDataSetInvalidated();
		}
	}
}